Siemens SINUMERIK 840D sl, Function Manual

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Detailed Description
2.4 Tool radius compensation 2D (TRC)
Basic logic functions: Tool Offset (W1)
70
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
2.4.4.4 System variables
Points P
3
and P
4
can be read in the WCS as system variables during approach.
$P_APR: Read P
3
(start point) in WCS
$P_AEP: Read P
4
(contour start point) in WCS
=1 If the content of $P_APR and $P_AEP is valid, i.e., if these contain the
position values belonging to the last SAR approach block programmed.
$P_APDV
=0 The positions of an older SAR approach block are read.
Changing the WCS between the SAR block and the read operation has no effect on the
position values.
2.4.4.5 Supplementary conditions
Supplementary conditions
•
Any further NC commands (e.g., auxiliary function outputs, synchronous axis movements,
positioning axis movements, etc.) can be programmed in a SAR block.
These are executed in the first subblock on approach and in the last subblock on
retraction.
•
If the end point P
4
is taken not from the SAR block but from a subsequent traversing
block, the actual SAR contour (straight line, quadrant or semicircle) is traversed in this
block.
The last subblock of the original SAR block does not then contain traversing information
for geometry axes. It is always output, however, because further actions (e.g., single
axes) may have to be executed in this block.
•
At least two blocks must always be taken into consideration:
–
The SAR block itself
– The block, which defines the approach or retraction direction
Further blocks can be programmed between these two blocks.
The number of possible dummy blocks is limited with the machine data:
MD20202 $MC_WAB_MAXNUM_DUMMY_BLOCKS (Maximum number of blocks with no
traversing motions with SAR).
•
If tool radius compensation is activated simultaneously in an approach block, the first
linear block of the SAR contour is the block, in which activation takes place.
The complete contour generated by the SAR function is treated by tool radius
compensation as if it has been programmed explicitly (collision detection, calculation of
intersection, approach behavior
NORM
/
KONT
).
•
The direction of the infeed movement and the position of the circle plane or the helix axis
are defined exclusively by the active plane (
G17
-
G19
) - rotated with an active frame
where appropriate.
•
On approach, a preprocessor stop must not be inserted between the SAR block and the
following block, which defines the direction of the tangent.
Whether programmed explicitly or inserted automatically by the controller, a preprocessor
stop results, in this case, in an alarm.